I use a lot of my extra batting in rag quilts. Small pices to large ones. I have sewn it together and used in bigger projects too. I haven't had any problems.

Zigzag for me too! Works great - never had a problem with it in a finished quilt

Here's the web site to the iron on tape for putting batting together.. It really does work great!! I quilt for others and almost always when they zig/zag the batting together it either has holes or it puckers..this works great!!
http://www.heatpressbattingtogether.com/
Judy

I like to overlap my batting pieces and make a wavy cut, removing the short pieces and hand basting the butted edges. I find zig-zag stitching compresses the batting more than I like. I haven't used the product made for fusing batting together, but I like to hand quilt and wonder if that would make the batting harder to quilt in the fused area?

I don't butt them together, but I overlap them by about 1/2". Then I use my fingers to pull the edge for I pull out enough "fluff" to make the edges feather out. I do that on the front and the back. By the time I'm done, there is no noticeable bump in the quilt and I KNOW it's not going to come apart.

I butt them together and zig zag. It comes out fine especially after you machine quilt whatever you use it in. I put a whole bunch of strips together side by side that I had left from trimming and used the piece for potholders or hot mats. Can't waiste that stuff you know. Yes it is COLD her in Maine.

I like to use a zig zag stitch, make it loose, adjust your tension so that the stitches don't sink clear into it :D:D:D

I went into the website for the tape, ordered 3 rolls, my zig-zag always puckers & this looks like the cat's meow!!

This is how i cut them, too. Butt the edges, too, but I do a hand baste rather than a machine stitch as it give it less of a visible line. I mostly save the leftovers for tablerunners.

Buy Fusible Interfacing cut it in 2" strips and join your left over batting that way, This works great and is really an inexpensive way to use up all your scraps